Recording head



MayZl, 1940. c. LoEB ET Al.

RECORDING HEAD Filed June 5, 1939 wlmi amg

w @www y Patented May 21, 1940 UNITED STATES PATENT ori-ics Carl Anderson,

Oak Park, Ill., assignors tol Actino Laboratories, Inc., a corporation of Illinois Application June 3, 1939, Serial No. 277,272

7 Claims.

This invention relates to a recording head.

An object ci the invention is to provide a much simpler structure which is extremely sturdy and adapted for long use. A further object is to provide a recording head which is faithful and accurate in recording operations and whichl may be constructed of very few parts. A still further object is to provide a recording head which does not deteriorate except after extremely long periods of usage, and which avoids the use of rubber and like materials which deteriorate rapidly in time. Other specic objects and advantages will appear as the specification proceeds.

The invention is illustrated, in a preferred embodirnent, by the accompanying drawing, in

Which- Figure 1 is a side view in elevation of a recording head embodying my invention; Figure 2, a longitudinal sectional view, the section being taken-as indicated at line 2 of Figure 3; Figure 3, a sectional view, the section being taken as indicated at line 3 of Figure 1; Figure 4, a sectional View, the section being taken as indicated at line 4 of Figure 3; Figure 5, a transverse detailed sectional view, the section `being taken as indicated at line 5 of Figure Ll; Figure 6, a bottom plan view of the spring plate or .fulcrum employed; and Figure '7, a broken sectional view showing the methodv of attachment of the armature to the spring plate.

In the illustration given, Ill designates a metal casing in which the parts are housed. A supporting metal plate II is secured to the back of the housing and a permanent magnet I2 in the shape of a horseshoe is confined against plate II by an outer plate I 3 and screw M. Secured to plate II by welding, or other suitable means7 are the field metal piecesl which provide between them a chamber for the coil IB. The coil I6 is supported between two insulating paper strips Il and I8. Wires I9 extend through the top of the casing and connect their inner ends with the coil I6.

The eld pieces. i5 have horizontal flanges 29 46 which are slightly spaced apart and provide an opening through which the armature 2| extends into the space between the arms of the magnet I2.

To the lower ends of the field pieces I5 are se- 50 cured the ends of a metal spring plate 22. In order to secure the armature 2l to the spring 22 in a permanent manner, and while adding a minimum of weight to the armature, we employ the following extremely satisfactory method.

,65 The armature 2| is provided at its lower end (Cl. Uilm-100.41)

with a tubular portion 23, and this, after the armature is in position, is spun over an angular piece 24 to form the permanent anchorage illustrated in Figure 7. It will be observed that the armature 2i is provided above the spring with an 5 enarged body portion 25 which has at its bottom a shoulder bearing against the spring plate 272. By bending over the tubular portion 23 in connection with the collar of the member 24, an extremely sturdy yand permanent connection i's l0 made while at the same time `adding very rlittle weight to the armature. It will be noted that the member 24.1 has a horizontal flange portion which rest-s against the bottom of the plate 22 and then at its inner end a depending collar portion about l5 which the iiange 23 of the armature is spun.

The armature 2| is provided with the usual slot 25 adapted to receive the cutter pin 21 and the cutter is locked in position by the threaded handle member 28. f 20 The casing I is provided with a bottom plate 29 provided with a relatively large opening 30 through which the cutter pin 21 freely extends.

Operation In the operation of the device, current passes through the two wires I8 leading from the sound actuated source and ows through the coil I6. The magnetic eld produced inresponse to the irregularities of the current causes the upper por- 30 tion of the armature to swing laterally. The flexible spring 22 serves as a fulcrum upon which the armature and pin swing so that the point of the pin, in traversing the recording means, moves laterally in the longitudinal `track thereon. In 35 this operation, it will be observed that the armature 2l is integrated through the connections described with the spring plate 22 and that the plate serves as a support as well as a fulcrum for the armature. The result is a faithful recording o of the sound upon the record.

lt will be observed that the structure is extremely simple and sturdy, consisting of few parts which can bereadily assembled. Deteriorating parts heretofore employed are avoided. The ful- Crum and dampening material, employed in the recording heads largely used today and which are made oi elastic material such as rubber which deteriorates under weather conditions after a relatively short period of time, are eliminated while at the same time a recording head is produced which is believed to be more accurate in operation.

While we have described the structure in detail, it will be understood that the details are given for the purpose of setting forth a clear modifica-tion employing the invention and that such details may be varied widely by those skilled in the art without departing from the spirit of our invention.

We wish it to be understood that we do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

We claim:

l. In a recording head, a frame, means responsive to variations in an electric current for varying a magnetic eld, a spring plate member carried in said frame, an armature fulcrumed upon said spring member and supported thereby within Said iield for lateral pivotal movement, and a cutter member secured to said armature.

2. In a recording head, a frame, a lat spring supported by said frame, an armature secured to said spring, means responsive to variations in current for varying the magnetic eld about the upper portion of said armature to produce lateral movement thereof, and a cutter member secured to the lower portion of said armature.

3. In a recording head structure of the class set forth, a casing, a permanent magnet secured within said casing, a at spring supported below said magnet with the central portion of the spring free for movement, an armature having its lower portion rigidly secured to and fulcrumed upon said spring and having an upper portion extending through a coil into a magnetic field, electric connections to said coil, and a cutter member secured to said armature.

4. In a structure of the class set forth, a frame, a flat spring supported therein at its ends, means responsive to variations in an electric current for varying the magnetic eld therein, an armature having its upper portion extending into said magnetic eld and having its lower end portion extending through an opening in said spring, a collar below said spring, the lower end of said armature being spun about said collar, said armature having a shoulder on the side opposite said collar engaging said spring whereby said armature is ixedly secured to said spring.

5. A method of assembling an armature provided with a hollow lower portion and with a shoulder to a at spring comprising perforating the spring and passing the lower' end of. the armature therethrough until the shoulder of the armature rests against the spring, inserting a collar member over said hollow end of the armature and against said spring, and then spinning the hollow portion of the armature about said collar.

6. The method of forming a lightweight armature and at spring connection comprising: peri'orating a flat spring, extending an armature having a shoulder thereon through said spring until the shoulder rests thereon, inserting a washer member over said armature and against the bottom portion of said spring, said washer having a depending collar, and spinning the lower portion of the armature about said collar.

7. In a recording head of the class set forth, a casing, a permanent magnet secured therein, eld pieces secured below said magnet, a coil supported between said eld pieces and provided with electric wire connections, a flat spring hav ing its ends secured to the eld pieces and having a flexing portion therebetween, an armature extending between said eld pieces and through said coil, said armature having its lower portion extending through and secured to said spring,

and a cutter member secured to said armature.

CARL LOEB. MORRIS A. GILMAN. CARL ANDERSON. 

